The present invention relates in general to a gas compressor for, for example, a refrigerating apparatus and an air conditioning system, and more particularly to a scroll compressor in which air or other gas is compressed to increase its pressure. Generally, the scroll compressor has an orbiting scroll member which includes an end plate and a spiral member or wrap formed substantially in an involute curve and attached to one surface of the end plate in an upstanding position, and a fixed scroll member which is formed complementary to the orbiting scroll member and is arranged in a juxtaposed relation with the wraps of both members being fitted closely together. The orbiting scroll member is moved in an orbiting motion while the rotation of it on its own axis is inhibited by an Oldham's ring disposed between, for example, the orbiting scroll member and a main frame or a housing. The orbiting movement of the orbiting scroll member reduces the sealed space or fluid pocket defined by the two scroll members, and thus compresses a gas therein to increase its pressure.
A structure and operational mechanism of the scroll compressor as described above are disclosed in Japanese Patent Publication No. 56-28237 published June 30, 1981, which will be explained presently. With reference to FIG. 4, the scroll compressor 50 has a fixed scroll 53 member having a wrap 52 in an involute curve on an end plate 51, and an orbiting scroll member 56 which is formed complementary to the fixed scroll member 53 and has an end plate 54 and a wrap 55 so that the two scroll members are arranged in a juxtaposed relation with the two wraps being fitted closely together. A stationary member 58 is fixed to the fixed scroll member 53 and an Oldam ring 57 is provided between the stationary member 58 and the orbiting scroll member 56. The fixed scroll member 53 has an exhaust opening 59 at a center of the end plate 51 so that a gas which has been compressed by a gas pocket formed by the wraps of the two scroll members 53, 56 is exhausted from the exhaust opening 59. The exhaust opening 59 is opened and closed by a check valve 61 to prevent a back-flow of a fluid, which has been compressed and exhausted from the exhaust opening 59, to a lower pressure side in the scroll compressor when the operation of the system is stopped so that reverse rotation of the orbiting scroll member is prevented.
However, the scroll compressor disclosed in the above-described Japanese Patent Publication has the disadvantage that the check valve is repeatedly opened and closed during operating thus producing noise.